On June 27, a plane carrying Wen Jiabao made a “technical” stop on the island of Terceira, in the Azores. Following an official greeting by Alamo Meneses, the regional secretary of environment of the sea, the Chinese premier spent four hours touring the remote Portuguese outpost in the middle of the Atlantic Ocean.

Wen’s Terceira walkabout, which followed a four-nation visit to South America, largely escaped notice at the time, but alarm bells should have immediately gone off in Washington and in European capitals. For one thing, Wen’s last official stop on the trip Santiago, the capital of Chile. Flights from Chile to China normally cross the Pacific, not the Atlantic, so there was no reason for his plane to be near the Azores. Moreover, those who visit the Azores generally favor other islands in the out-of-the-way chain.

Terceira, however, has one big attraction for Beijing: Air Base No. 4. Better known as Lajes Field, the facility where Premier Wen’s 747 landed in June is jointly operated by the U.S. Air Force and its Portuguese counterpart. If China controlled the base, the Atlantic would no longer be secure. From the base’s 10,865-foot runway on the northeast edge of the island, Chinese planes could patrol the northern and central portions of the Atlantic and thereby cutair and sea traffic between the U.S. and Europe. Beijing would also be able to deny access to the nearby Mediterranean Sea.

And China could target the American homeland. Lajes is less than 2,300 miles from New York, shorter than the distance between Pearl Harbor and Los Angeles.

Lajes is certainly the reason Wen went out of his way to win friends in Terceira. For years his country has been trying to make inroads into the Azores and waiting for opportunities to pounce. There is nothing the Chinese can do if the U.S. stays, but Pentagon budget cutters, according to some observers, are planning to make Lajes a “ghost base.”

At one time, the facility was critically important. During World War II, the airfield was instrumental in hunting U-boats, and in the Cold War the base helped the West track the Soviets. Lajes was a busy transit point in the Gulf War. It was one of the spots where the Space Shuttle could have landed in an emergency.

Now Lajes is home to the USAF’s 65th Air Base Wing, which supports American and NATO aircraft transiting the Atlantic, and it hosts various other American military units. Its role, nonetheless, is greatly diminished. Peace in the North Atlantic and advances in air-to-air refueling have decreased the importance of the strategic runway, which is now rarely used by the U.S.

So from a purely military point of view, the decision to cease operations at Lajes makes sense. The effective closure of the field, however, would send Terceira into a tailspin. While agriculture forms the basis of the island’s economy, the base directly accounts for about one in 20 jobs there. Unemployment is already high, about 10 percent. If Terceira is to have any future, the Portuguese government will have to find a new major tenant for Air Base No. 4.

In recent years, Beijing has identified Portugal as its entry point into Europe, and Chinese officials now know their way to Lisbon. It is in this context that Portuguese officials are already thinking about the planned closure of Lajes Field. They don’t want to invite the Chinese in, but they have quietly indicated they will have no choice if the U.S. Air Force decides to leave the base.

“We have a close relationship with Portugal,” the Defense Department told NRO when asked about the planned closure of Lajes and Beijing’s apparent interest in taking it over. “They are an important NATO ally and bilateral partner, and we continue to discuss our strong defense cooperation, in Portugal and around the world.”

We will, as a longtime ally, need to work closely with Lisbon over an especially thorny issue, but in the interim, there are things that can be done. For instance, it’s not entirely clear why the U.S. Africa Command should be based at Kelley Barracks, outside Stuttgart. A transfer of the approximately 1,500 staff there to Lajes, which is much closer to Africa, would solve the problem overnight, and the move might actually improve Africom’s effectiveness.

There are undoubtedly other stopgap solutions that the Pentagon could implement. None of them will be perfect, but all of them would be better than having Beijing’s red flag flying over the Atlantic — and permitting Chinese aircraft to patrol the waters connecting America to Europe.